Pengaruh Praperlakuan Alkali dan Asam terhadap Karakteristik Mutu Bakto Agar dari Rumput Laut Gelidium sp

Abstract

Ekstraksi bakto agar dari rumput laut merah Gelidium sp. asal Pameungpeuk, Jawa Barat dengan praperlakuan alkali dan asam telah diteliti. Pada praperlakuan alkali digunakan NaOH dengan variasi konsentrasi 4, 5, dan 6%. Asam yang digunakan yaitu CH₃COOH dengan variasi konsentrasi 0,5% dan 1,0%. Parameter mutu yang diamati meliputi kadar air, kadar abu, kadar abu tak larut asam, kadar sulfat, gugus fungsi, rendemen agar, kekuatan gel, viskositas, titik leleh dan titik jendal, sineresis, dan angka lempeng total. Bakto agar terbaik diperoleh dari praperlakuan dengan konsentrasi NaOH 4% dan CH₃COOH 0,5% yang telah memenuhi beberapa persyaratan mutu bakto agar komersial untuk parameter kekuatan gel, kadar air, kadar abu, dan kadar abu tak larut asam. Karakteristik mutu dari praperlakuan tersebut adalah kadar air 13,69±1,02%, kadar abu 4,24±1,28%, kadar abu tak larut asam 0,54±0,25%,  kadar sulfat 1,55±0,36%, rendemen 9,19±2,21%, kekuatan gel 1464,98±109,09 g/cm2, viskositas 42,75±24,40%, sineresis 2,76±0,12%, titik jendal 20,50±2,12  °C, dan titik leleh 95,25±1,06 °C. Praperlakuan dengan konsentrasi tersebut juga memiliki nilai Angka Lempeng Total  (ALT) yang sama dengan bakto agar komersial.

Abstract

Bacto agar extraction from red seaweed Gelidium sp. from Pameungpeuk, West Java with alkali and acid pretreatment had been conducted. NaOH with concentration of 4, 5, and 6% was used for alkali pretreatment while CH₃COOH at concentrations of 0.5% and 1.0% (v/v) was used for acid pretreatment. The quality parameters investigated were moisture content, ash content, acid insoluble ash, sulphate content, functional groups, yield, gel strength, viscosity, melting point, gelling point, syneresis, and total plate count. The best quality of bacto agar was obtained by using 4% alkali pretreatment and 0.5% CH₃COOH. This pretreatment has fulfilled the specification of commercial bacto agar for moisture, ash, acid inslouble ash content, and gel strength parameter. The properties of bacto agar from this pretreatment were moisture content 13.69±1.02%, ash content 4.24±1.28%, acid insoluble ash content 0.54±0.25%, sulphate content 1.55±0.36%, yield 9.19±2.21%, gel strength 1464.98±109.09 g/cm2, syneresis 2.76±0.12%, gelling point 20.50±2.12 °C, and melting point 95.25±1.06 °C. This pretreatment also gave the same result as the commercial bacto agar for the total plate count.